Control means for refrigerating apparatus



sept. 19, 1961 21M/1N 3,000,186

CONTROL MEANS FOR REFRIGERATING APPARATUS Filed March 27, 1959 2SI'Leecs--SheetI 1 INVENTOA Leonard J. Mann His Attorney Sept. 19, 1961J. MANN 3,000,186

CONTROL. MEANS FOR REFRIGERATING APPARATUS Filed March 27, 1959 2Sheets-Sheet 2 IN1/NTM Leonard J, Mann Byw-wgw His Attorney UnitedStates Patent O 3,000,186 CONTRGL MEANS FOR REFRIGERATING APPARATUSLeonard J. Mann, Dayton, Ohio, assignor to General Motors Corporation,Detroit, Mich., a corporation of Delaware Filed Mar. 27, 1959, Ser. No.802,524 8 Claims. (Cl. 62-153) rllhis invention relates to refrigeratingapparatus and more particularly to frostless refrigerators.

This invention is a continuation-impart of my copending applicationsSerial No. 617,170 filed October 19, 1956, now Patent No. 2,907,180, andSerial No. 633,109 led January 8, 1957, now Patent No. 2,912,834, towhich further reference may be made for additional details.

In frostless refrigerators, such as are disclosed `in said applications,the evaporator is isolated from the compartments which are cooled by the'circulation of air from the evaporator. This prevents frosting in boththe above and below freezing compartments but the frost does collect onthe evaporators. It has been found that occasionally frost will collectin the below freezing compart ment when its door is left open for aconsiderable period of time and ythe air circulation is stopped.

It is an object of this invention to prevent the formation of frost in afrostless refrigerator when the door is opened.

It is another object of this invention to insure circulation of airthrough the below freezing compartment whenever its door is opened.

These and other objects are attained in the two forms shown inthedrawings in which the freezing evaporator is located beneath the belowfreezing compartment while the above freezing compartment is eithercooled by air circulation from this evaporator or another evaporatorconnected in series with it. To prevent any formation of frost in thebelow freezing compartment when the door is left open for considerableperiods, I provide a double throw switch actuated by the opening andclosing of the door which will insure operation of the fan forcirculating the below freezing compartment air through the evaporatorbeneath and then returning the air to the compartment whenever this dooris open.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings wherein preferred embodiments of the present invention areclearly shown.

In the drawings:

FIGURE 1 is a vertical sectional view through a single evaporator formof frostless refrigerator embodying my invention;

FIGURE 2 is a vertical sectional view through a two evaporator frostlessrefrigerator embodying my invention;

FIGURE 3 is a wiring diagram for the single evaporator refrigeratorshown in FIGURE 1; and

FIGURE 4 is a wiring diagram for the two evaporator refrigerator shownin FIGURE 2.

Referring now more particularly to FIGURE l, there is shown an insulatedrefrigerator cabinet 20 containing an above freezing compartment 22located above the below freezing compartment 24, with the compartmentsseparated by an insulated wall 26. 'Ihe compartments respectively areprovided with insulated doors 28 and 30. Beneath .the false metal bottomwall 32 of the freezing compartment 24 is a cross iin and tubeevaporator 34 having vertical fins extending from front to back.

'This evaporator 34 is maintained at temperatures below ice freezing,such as 10 F., by the motor-compressor unit 36 which withdrawsevaporated refrigerant through the suction conduit 38 and forces thecompressed refrigerant into the condenser 40 from which the liquidrefrigerant is supplied through a flow restricting capillary tube 42back into the evaporator 34.

At the rear of the freezing compartment 24 is a centrifugal fan 44driven by an electric motor 46 for withdrawing air from the rear of theevaporator 34 through the duct 48 and discharging the air through twodischargel ducts 50 and 52. The discharge duct 50 extends up` wardlybehind the rear wall of the compartment 22 and discharges into thiscompartment through an upper opening 54. Air is withdrawn from thecompartment 22 through lower side wall openings 56 connecting with theduct S8 surrounding the front of the compartment 24 which dischargesinto the plenum chamber 60 at the front of the evaporator 34. Air isdischarged from the duct 52 through openings 62 at the upper rear of thecompartment 24 which provides even distribution of air ow through thecompartment 24. 'This air isV then drawnv through openings 64 into theduct 58.

As shown in FIGURE 3 between the supply conductor L1 and the supplyconductor L2, there is connected a thermostat 66 including a thermostatbulb 68 mounted at the rear of the evaporator 32 and connected bycapillary tube to a bellows actuator 70 operably connected to the switch72. This switch 72 connects the supply conductor L1 and the conductor 74with the conductor 76 and the motor-compressor unit 36. Themotor-compres-V sor unit 36 is connected by the conductor 78 to onetermi-V nal of the double throw defroster switch 82 normallyV held inengagement with the contact 82 by the defrost control 84. The doublethrow switch 82 is connected by'- the conductor 86 to the line L2 tocomplete the energiz'V ing circuit of the motor-compressor unit 36.

Since frost gradually accumulates upon the evaporator because of its lowtemperature, the defrost control 84 periodically moves the double throwswitch 82 into engagement with the contact 88 to deenergize themotorcompressor unit 36 yand to complete the energization of the defrostheater 90 located in heat transfer relation with the evaporator 34. Thedefrost control as well as the heater 90 is connected to the conductorL1 by thel conductor 92. The defrost control 84 is permanently connectedto the supply conductor L2. By the operation of the defrost control 84,vthe heater 90 is periodically connected through the contact 88 toswitch 82 and the conductor 86 with the supply conductor L2 to heat theevaporator 34 while the motor-compressor unit 36 is idle for defrosting.

The fan motor 46 is normally connected by the double throw door switch94 through th conductors 96 and 98 in series with the thermostat 66 sothat the motor-corn# pressor unit 36 and the fan 46 cyclesimultaneously. A switch 121, normally closed, connects the motor 46 tothe contact 80 so that it is likewise deenergized and stopped during thedefrosting period. The switch 121 is operated to open position by theopening of the door 28. This stops the motor 46 and the fan 44 duringthe time the door 28 is open. The double thro-w switch 94 is normallyheld in closed position against the force of they spring 123 by the door30 when it is in the closed posi! tion through the use of a plunger 125.IIn this position, the fan motor 46 is connected in series with thecontact" 72. The doors 28 and 30 are opened independently of each other,and normally only one of these doors will be opened at a time.

Under normal conditions of operation, no frost will collect in either ofthe compartments 24 or 22. However, should the door 30 be left open forconsiderable periods of time, there is a possibility under conditions ofhighhumidity that frost may ycollect upon the ice tray 127 andthe bottom32 of the compartment 24. To prevent this, the double throw switch 94 isoperably connected by the plunger 125 to the door 30 to release theswitch 94 so. that. it will move to its vdottediline positionconnecting( with the contact 129` and the conductor 131 with the supplyconductr L1 so as to shunt the thermostat 66 and its switch 72 and causecontinuous operation of the fan motor 46 as long asY the door 30 isopen. The reclosing of the door 30 will move the switch 94 back to itsfull line position to again make the 'operation of the fan motor 46dependent upon the closing of theswitch 72. The operation Vof the fanwhile the door 30 is open will prevent accumulation of frost withinthccompartment 24. If the door 28 is frequently opened at the same timethe door 30 is open, the'door switch 121 may be shunted by the manualswitch 133 andthe conductors' 135 fand 137 to insure the operation ofthe fan motor 46. Y

IIn FIGURE 2, the below freezing compartment 224 is similarly cooled bythe evaporator 234' beneath the false bottom 232. Air is similarly drawnfrom the compartment 24 through the openings*2,64 into the duct 258which conducts the `air into the plenum chamber 260 at the front of theevaporator. The air is drawn through the evaporator 234 from front torear by the fan 244 driven by the electric motor 246. This air isdischarged through the duct 252 at the rear and issuesV through theapertures 262 in the rear. The evaporator 234 is defrosted by theelectric,` heater 290, and the defrost water is collected from a drainpan 301, passing through a liquid trap 302 from which it ows into thedrain pan 303.

.bove the compartment 224 is the above freezing con-rpartment 222 havingits own evaporator 304 behind a false rear wall 300. VAiris drawn fromthe bottom of the compartment 222-.by thel fan 305 driven by anelectricv motor 306 and circulated through the passage 307 around theevaporator 304 and discharged through openings 308 atl the top back intothe compartment 222. The fan motr306 is controlled by a thermostat 309adjacent the outlet 308 to control the temperature of the compartment222 independently of the compartment 224. The compartments 222 and 224yare provided with separate doors 228 and 230. The evaporator 304 isconnected in series with the evaporator 234; both are controlled by athermostat 268 set to provide a defrosting cycle of the plate 304 and tokeep the evaporator 234 below freezing temperatures at times. Y Thedefrost Water from the evaporator 234 is conducted by the conduit'310into the drain pan 303.

Similarly to FIGUREA 1, no frost will'normally collect eitherYcompartment. However, should the door 230 be left open'for prolongedperiods, there is a danger that ost Will accumulate on the false bottom232Y and possibly the inlet duct 248. To prevent this, thedouble throwswitch'294 is provided Which normally connects ythrough the conductor296 to themcontact 272 of the thermostatic vswitch 266 actuated by thebellows 270 in accordance with the temperature of the "thermostat bulb268.v '.The'th'ermostat 266 is merely diagrammatically shown and isprovided with a snap action mechanism not shown and suitablevvadjustment to cause it to yclose at a temperatur'e'of about 35 F. andto open at a temperature of about 41.05V E. This setting Will insure thedefrosting of the evaporator 304 during each olf cyclewhile theevaporator 234 is maintained at below freezing temperatures at alltimes.

v"These evaporators 234and 304 are connected in Vseries with each otherand withiaI refrigerant liquefying means` which includes asealedmotor-compressor unit 236 connected through the conductors 274 and 276as well as the switch 272 with the supply conductor S1. VTheioppositeterminal'of the motor-compressor nnit 236 is connected by the conductor278 with Vthe upperV contact '280 of the double throw defroster' switch282 controlled by the defrost control 284. The switch 282 eitherconnects the motor-compressor unit S2736 and the fan motor 246 throughlthe conductor 286 withthe supply conductor S2`orit dissannscts thenaief-@nasser unit '.236 slid the, fen

motor 246 by moving into engagement with the contact 288 to connect withthe defrost heater 29,0 to defrost the evaporator 234. The defrostcontrol 284 and the heater 290 are connected bythe conductor 292 withthe supply conductor S1. The fan motor 246 may be stopped through theopening of the door switch 321 by the opening of the'above freezingcompartmentdoor 228. However, this switch may be Vshunted by the switch333.

The fan 2,46jis madeY to operate upon the openingv of the door 230'bythe plunger 325 and the spring 323'whieh moves it into engagement withthe contact 329 to connect through the conductor 331 with the supplyconductor S1. This will insure the operation of the fan motor 246whenever the door 230 is opened. Through this arrangement,

frost is prevented from forming in the below freezingV compartmentYshould the door be left open for considerable periods 'of time. v

'While theembodimentsv of the present invention ask hereindisclosed,-constitute preferred forms, it is to be', understood thatother forms might be adopted.

What is claimed is as follows:

l. A refrigerator including an insulated cabinet having above freezingand below freezing compartments separated from each other, refrigerantliquefying and evaporating means located outside'said compartments, fanmeansv for circulating air from said compartments into heat trans ferwith said evaporating means and return, thermostatic switch means forenergizing and deenergizing said liquefying meansV and said fan means, adoor for said below freezing compartment, andra double throw switchoperated by` the closing of the door to a position connecting said fanmeans in serieswith said thermostatic switch meansl andl operated by theopening of the door to a position connesting the fan means in' shuntwith Vthe thermostatic switch means. Y

2. A refrigerator including an insulated cabinet having above freezingand below freezing compartments separated from each other, refrigerantliquefying and evaporating means located outside said compartments, fanmeans for circulating air from said compartments into heat transfer withsaid evaporating means and return, thermostatic means for controllingsaid liquefying means, and said fan means, a door for said belowfreezing compartment, a first supply conductor connected to saidthermostatic means, a second supply conductor, an electric defrostVheater in heat transfer relation to said evaporatingLA means having oneterminal connected to said first supply conductor, a defrost controlalternately connecting in one alternate position said liquefying and fanmeans -to said second supply conductor and in the other alternateposition connecting said'heater to'said second supply .conductor, a doorfor said below freezingeompartment, a double throw switch operated bythe closing of the door for connecting the fan means in series with-saidthermostatic means and operated by the opening of the door forconnecting'said fan means directly to said lrst supply conductor, saiddefrost control having means preventing energization of said fan meansduring the energization-'ofi saidheater. l

3. A refrigerator including an insulated cabinet containing a belowfreezing compartment and an above freezing compartment, a'rst'evaporatorand a second evapo- 'rator outside saidY compartments, Vrefrigerantliquefying d ing of said door to shunt said thermostatic switch means tooperate said rst fan means.

4. A refrigerator including an insulated cabinet containing a belowfreezing compartment and an above freezing compartment, a firstevaporator and a second evaporator outside said compartments,refrigerant liquefying means operatively connected in series circuitwith said evaporator, a first fan means for circulating air from saidbelow freezing compartment into heat transfer with said rst evaporatorand return, a second fan means for circulating air from said abovefreezing compartment into neat transfer with said second evaporator andreturn, thermostatic switch means for cycling said liquefying means andsaid first fan means, a door for said below freezing compartment, adouble throw switch operated by the closing of said door to connect saidfirst fan means in series with said thermostatic switch means andoperated by the opening of said door to shunt said thermostatic switchmeans to operate said first fan means, and a second thermostatic meansresponsive to the temperature of said above freezing compartment forcontrolling said second fan means independently of said door and saidthermostatic switch means.

5. A refrigerator including an insulated cabinet having a below freezingcompartment, refrigerant liquefying and evaporating means locatedoutside said compartment, fan means for circulating air from saidcompartment into heat transfer with said evaporating means and return,thermostatic means for controlling said liquefying means and said fanmeans, a door for said below freezing compartment, and control meansmechanically connected to and mechanically operated by said door anddirectly and immediately responsive to each opening of said door forinsuring operation of said fan means whenever said door is opened.

6. A refrigerator including an insulated cabinet having a below freezingcompartment, refrigerant liquefying and evaporating means locatedoutside said compartment, fan

means for circulating air from said compartment into heat transfer withsaid evaporating means and return, thermo- Static switch means forenergizing and deenergizing said liquefying means and said fan means, adoor for said below freezing compartment and a double throw switcharrangement operated by the closing of the door lto a positionconnecting said fan means in series with said thermostatic switch meansand operated by the opening of the door to a position connecting the fanmeans in shunt with the thermostatic switch means.

7. A refrigerator including an insulated cabinet having a compartment tobe cooled, refrigerant liquefying and evaporating means located outsidesaid compartment, fan means for circulating air from said compartmentinto heat transfer with said evaporating means and return, thermostaticmeans for controlling said fan means, a door for said compartment, andcontrol means mechanically associated with and mechanically operated bysaid door and directly and immediately responsive to each opening ofsaid door for insuring operation of said fan means whenever the door isopened.

8. A refrigerator including an insulated cabinet having a compartment tobe cooled, refrigerant liquefying and evaporating means located outsidesaid compartment, fan means for circulating air from said compartmentinto heat transfer rwith said evaporating means and return, thermostaticswitch means for energizing and deenergizing said liquefying means andsaid fan means, a door for said compartment, and a double throw switcharrangement operated by the closing of the door to a position connectingsaid fan means in series with said thermostatic switch means andoperated by the opening of the door to a position connecting the fanmeans in shunt with the thermostatic switch means.

References Cited in the file of this patent UNITED STATES PATENTS2,801,525 Bixler Aug. 6, 1957

